Control for permanent mold distortion



H. s'. LEE Er AL CONTROL FOR PERMANENT MOLD DISTORTION Filed June 23, 1925 .IIIIIIII.

May 18 1926.

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2 Sheets-Sheet 2 H. S. LEE ET AL CONTROL FOR PERMANENT MOLD DISTORTION Filed June 25. 1925 May 18 1926.

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Patented May 18,. 1926.

UNITED STATES PATENT OFFICE.

HARRY S. LEE AND AMOS E. CHAFFEE, OF PLYMOUTH, MICHIGAN; SAID CHAFFEE ASSIGNOR TO SAID LEE.

CONTROL FOR PERMANENT MOLD DISTORTION.

Application filed June 23, 1925. Serial' No. 39,053.

tion of the distortion depends both on the metal used .and the design of the mold sections. v

In order to get a ,fairly accurate casting, and also to prevent leakage along the parting line, it is desirable in some way to control this distortion or bowing action. This bowing action is particularly evident in molds where they are relatively long and thin.

In the'prior application of Harry S. Lee, Amos E. Chadee `and Fred Millard, Serial No. 10,830, this condition is recognized, an a mechanical design for automatically affording a countervailing pressure is provided. There is also described in this prior application a lthermo-responsive element. This is claimed-only speciiically in connection with the mechanical design' which is relied upon chiefly to afford the automatically applied countervailing pressure. v

It is the object of the present invention to meet and furnish a solution of this mold distortion in quite a diderent way. This is accomplished in connection with the pres# ent invention by utilization of thermallyresponsive elements to aiord a countervailing thrust or tension, for the purpose of neutralizing these mold section distortions.

It will be recognized by the foundry man that these distortions will vary in amount and direction, and in accordance with the particular mold section design and the metal of which the same is constructed. There-` fore we have given several illustrations oi various molds, and have shown several forms of thermally-responsive elements which can be used to neutralize the bowing tendencies. rIhese, however, are by no means all the different forms of molds and distortions that one will meet in foundry practice with permanent molds, nor are they by any means the only waythat these distortions forces can be more or less neutralized by the interpositin elements. typical examples which come within the scope of our broad invention.

Referring to the drawings Fig. 1 is a cross section of a pair of mold sections where the mold sections tend to bend outwardly.

Fig. 2 is a section through a mold which has heavy ends and thin at the mid portion, where there will likely be a tendency of the mold sections to bow inwardly. This is a section taken on the line 2-2 of Fig. 3.

Fig. 3 is a cross section on the line 3-3 of Fig. 2.

Fig. 4 is a section of another; mold whereA there will be-a tendency of the mold sections to bow inwardly, and this is resisted by thermally-responsive tie-strips on the outd side of the mold.

Fig. 5 is a section of another mold in which the sections tend to bow outwardly, and where this is resisted by tie-inserts on the inside Yfaces of the mold.

In the form of mold shown in Fig. 1, the mold sections sometimes called the dies, are constructed of metal and are of such a design as experience has shown lthat there is a tendency to bow slightly outwardly. af-a designates the inserts on the outside faces of these mold sections. These inserts are of metal having a relatively higher co-,eiiicient of expansion than the metal of which the mold sections are mainly constructed.

It will therefore be apparent that when the inside walls of the mold heat up vby repeated casting operations they will tend to expand and bow the mold sections outwardly. However, the inserts will also heat up but not to as great a degree as the metal on the inside, but having a relatively greater coeiiicient of expansion the insert will expand approximately equally with the metal of the mold. Thus it will be evident that these forces tend to neutralize each other and countervail the bowing action.

We nd that vanadium chrome or nickel alloy, and numerous other metals, can be used for the purpose of inserts. rlhe selection of the metal may be readily made as the co-eicient o expansion of well known of suitable thermally-responsive They simply illustrate various metals can be readil learned, and utilized in countervailin w at has been observed to be the distortion in any given design of mold section or dies constructed of a 'ven metal. The character of the insert an size of the insert will have to be largely determined after experience has taught one the amount of distortion that is toA be met with ir a given design of die or mold section.

In some s ecial forms of mold sections or dies, it w1ll probably be found that the tendency of the sections to bow is toward the inside, particularly in certain forms of dies that have relativel thin mid portions and relatively heavy en s. In such a die the countervailing thermally-responsive element may be inserted in the meeting faces of the dies, as shown in Figs. 2 and 3.

In Fig. 4 is shown another use of a thermally-responsive element in neutralizing the distortion strains. In this figure is shown a set of mold sections in which, due to the design and the' metal of which they are made, .the bowing will be towards the center. To counteract this a different character of thermo-responsive element is employed, namely/, one which has a lessco-efiicient of expansion and consequently vthis becomes a tension member or tie member and tends to countervail the bowing action by tension applied to the two ends. n

In Fig. 5 the tendency of the dies is to bow outwardly, and here the tension inserts are placed in the meeting faces of the mold and these inserts are of` a material having a less co-eicient of expanslon, so that 1t im oses a tension stress'on the ends of the mo d section, which tends to resist the outward bowing. The same principle is involved in the thermally-responsive elements shown in Figs. 4 and 5, as m those shown in'Figs. 1, 2 and 3, exce t the former are tension members and the atter are pressure members.

What we claim is:

1. A pair of permanent mold sections tending to distort slightly when heating up, and thermally-responsive means for countervailing such distortion by interposing thermally controlled resistance thereto.

2. In a permanent mold, a pair of metal mold sections havin a tendency to bow when heated up, an thermally-responsive means for counteracting this bowing tendency by exerting a resistance.

3. In a permanent mold, a pair of metal mold sections having a tendency to distort or bow, and a, thermall -responsive element having a relatively di erent co-efiicient of expansion and properly placed to counteract such bowing tendenc 4. In a permanent mo d, the combination of a pair of mold sections which tend to bow, and an insert havinl a different coeicient of expansion which is calculated for neutralizing the expansion strain set up on the inside of the mold.

5. In a permanent mold, the combination of a pair of metal mold sections having a tendency to bow due to the heating up of the mold cavities, and a thermall -responsive element having a relativel di erent coeflicient of expansion proper y placed on mold sections, depending upon the direction 3f bowing to countervail this bowing tenenc 6. )'Tlhe method of countervailing the tendency of permanent metal mold sections to distort under heat, which comprises the determination of the direction of the distortion, and then the interposition at the proper place of a thermally-res nsive element of relatively different co-e cient of expansion which tends to neutralize such distortion.

'In testimony whereof we have aixed our I6 

